Mechanical bearings find many applications in various industries and are used in components that provide mechanical movement of parts and other components, within or to a manufacturing apparatus. In the semiconductor manufacturing industry, mechanical bearings are used in mechanical wafer transfer mechanisms that utilize robot arms and wafer gripping or receiving members to pick up and transfer the substrates to and from desired positions in the substrate processing manufacturing tool. These mechanical wafer transfer operations are highly precise operations and require the robot arms to be properly aligned and to move accurately. Deviation in the movement of the robot arm will cause its position to be out of alignment. When a wafer arm which is out of alignment or which moves improperly, picks up and transfers a semiconductor substrate, i.e. wafer, the transfer operation may result in scratching or breakage of the wafer, or any other of a number of detrimental aspects. To avoid the aforementioned problems which may result in contamination in the wafer processing apparatus, the movement of the robot arm must be smooth and accurate. Mechanical bearings are used to provide such accurate movement.
Mechanical bearings used for robot arms or other wafer transfer mechanisms typically consist of two metal rings filled with metallic or ceramic balls. The two metal rings are called the inner and outer raceways. The balls disposed in the raceways allow the raceways to rotate smoothly with respect to one another. A lubricant may be added to the raceways to coat the balls to reduce friction during movement. In many applications, however, the wafer transfer mechanism including the ball bearings, is exposed to extremely high temperatures that can cause the lubricant to degrade. As the lubricant degrades, it undergoes a chemical transformation that causes the lubricant to solidify. As the lubricant solidifies, the friction between the balls and the metal rings increases, rendering the robot arm movement less smooth, and less accurate. Additionally, the solidified lubricant can result in particles that may be released into the microenvironment of the transfer mechanism, directly onto the wafer or into the chamber or other processing member in which the wafer is processed. In many cases, the solidified lubricant may build up in particular areas causing severe particulate problems at those locations.
It would therefore be useful to provide a bearing that may be used in the semiconductor manufacturing industry and does not include the above described shortcomings.